German patent No. 27 59 561 discloses a telephone register or index of the latter type which is relatively flat and has a horizontal rectangular upper side upon which the telephone can be mounted.
This index was found to be suitable for standard telephones with the receiver positioned transversely of the telephone body which had an outline so that the upper surface of the telephone index could have a correspondingly square configuration.
More modern telephones often are somewhat elongated, can be provided in various lengths and may have the receiver accommodated longitudinally of the telephone body so that the outline of the latter may have a greater depth or length than its breadth.
Such telephones cannot be mounted on conventional telephone indexes which are designed for square-outline telephones without extending beyond the housing of the index in an unstable, unaesthetic, or unusable manner.